Bipyridine Periodic Mesoporous Organosilica: A Solid Ligand for the Iridium-Catalyzed Borylation of C—H Bonds

摘要

With the goal to obtain a molecularly defined iridium(I) heterogeneous C—H functionaliza-tion catalyst, a periodic mesoporous organosilica (PMO) containing bipyridylene moieties in a matrix of biphenylene units as ligand platform was designed and fully characterized. The material exhibits a high surface area with small mesopores in a vermicular arrangement, and the pore walls show a highly crystal-like character. After surface passivation with chlorotrimethylsilane and functionaliza-tion with chloro(l,5-cyclooctadiene)iridium(I) dimer [{IrCl(COD)}2] a molecularly defined Ir(I) surface complex was obtained according to EXAFS and UV-Vis spectroscopy. This functionalized material catalyzes the direct C-H borylation of arenes to yield the corresponding boronic esters and can be reused without significant loss of activity.